1. Field of the Invention (Technical Field)
The present invention relates to an apparatus for assessing the structure and detecting leaks underneath fluid storage tanks, other holding structures or fluid carrying pipelines. The present invention is also a method for using the apparatus for assessing and detecting leaks.
2. Background Art
Many different substances, such as water, chemical products, agricultural products, petroleum products, and waste have been stored or isolated in tanks or landfills, either on the surface of or below ground. Prolonged exposure to the environment tends to create the potential for leaks, leading to the possibility of contamination of soil and groundwater supplies, as well as the loss of the stored resource itself. Environmental regulations have become increasingly stringent in efforts to prevent such contamination. As a result, it has become imperative to detect leaks early, so as to avoid costly cleanup and perhaps irreversible damage.
Several inventions have been developed to detect leaks in storage tanks. Among these are U.S. Pat. No. 5,767,390, to Chapman, entitled System and Method for Storage System Leak Detection; and U.S. Pat. No. 4,770,028, to Flippo, entitled Hydrocarbon Tank Leak Detection System. These systems required the leaked substance to somehow reach the vertical tube. Not only did this eliminate the possibility of determining the location of the leak, but also the increased amount of leaked substance potentially necessary to reach the vertical monitoring well created a much larger amount of contamination to be cleaned and/or detoxified.
To help increase the sensitivity of the detection device, several inventions placed the monitoring pipes underneath the tanks. These devices included U.S. Pat. No. 5,305,631, to Whited et al., entitled Cathodic Protection and Leak Detection Process and Apparatus; U.S. Pat. No. 5,155,356, to Peters et al., entitled Apparatus and Method for Detecting Subterranean Leakage from a Large Storage Vessel. These devices detected leaks by the use of anodes or moisture-detecting probes, and do not sample the leaked substance.
U.S. Pat. No. 5,347,850, to Tuma, entitled Method for Detecting and Localizing Leaks in Above Ground Storage Tanks; U.S. Pat. No. 5,048,324, to Thompson, entitled Aboveground Tank Leak Detection System and Method, and U.S. Pat. No. 4,896,528, to Lewis, entitled Tank Bottom Leak Testing and Apparatus, also disclose the use of pipes placed beneath the tank. However, these inventions do not allow for precise localization of the leak, as they require the leaked substance be evacuated by air or vacuum. Due to the relatively short period of time the vacuum is activated, and the fact that such vacuum systems also lack a concentrating mechanism, the leaked substance may travel away from, rather than towards the sampling well or pipe.
U.S. Pat. No. 5,096,087, to Thomas, entitled Double Containment and Leak Detection Apparatus, discloses a method of detecting a leak within a tank in an internal baffle, and is not relevant.
Localization of the leak is a key issue when dealing with large holding structuresxe2x80x94the cost of total replacement is often prohibitive. The ability to determine location of the leak would be cost-effective both in terms of repair and cleanup.
The present invention is an apparatus and method for detecting leaks underneath holding structures. It may also be used to detect pipeline leaks. It successfully addresses the need for localization of leak detection, through the use of movable sampling units underneath the holding structures. The construction of the present invention results in an apparatus that is itself both inexpensive and easily monitored.
A preferred embodiment of the present invention comprises an apparatus for detecting leaks of holding structures, the apparatus comprising at least one perforated pipe disposed underneath the holding structure, and at least one sample container removably positionable within the pipe. The pipe is preferably disposed horizontally beneath the holding structure, and preferably disposed above a liner underneath the holding structure. Preferably, there is a plurality of pipes disposed approximately 1-8 feet apart. Preferably, the perforation style is slots, holes, or other apertures. The sample container preferably comprises a collection receptacle for dirt surrounding the pipe.
In a preferred embodiment of the apparatus, the sample container comprises a second pipe slidable in the perforated pipe. Alternatively, a plurality of sample containers are disposed at intervals within the pipe, and further comprise a location delineator for identification of positioning of the sample containers, and consequently identification of the location of the leak. Preferably, the sample containers are in series, preferably detachably connected to each other. The sample container comprises at least one wheel, or alternatively comprises a low-friction, slidable bottom surface, preferably Teflon(copyright).
In a preferred embodiment of the present invention, the sample container comprises an absorbent/adsorbent material disposed within, preferably comprising bentonite, sand, or water, and further comprises a compound indicator in the sample container for detecting a compound provided to the substance in the holding structure which is leaking. Alternatively, the apparatus further comprises a reference material in the sample container for determining differences in potential. In an alternative embodiment, the sample container comprises a reference electrode.
A preferred embodiment of the present invention further comprises a disposing and retrieving device for the sample containers to be disposed and retrieved in the pipe, and preferably comprises a loop, hook or magnet on at least one end for retrieving the container. The disposing and retrieving device preferably comprises cable, string or cord.
A preferred embodiment further comprises a disposing and retrieving activator to which the disposing and retrieving device is attached, preferably a spool, and preferably an independently-controlled activator for each pipe. Preferably, the independently-controlled activators share a common spool.
The present invention is also a method for detecting leaks from holding structures, the method comprising the steps of placing at least one pipe underneath the holding structure, disposing at least one sample container within the pipe, collecting at least one sample from around the pipe into the sample container, retrieving the sample container, and analyzing the sample to detect the leaked substance. Preferably, a perforated pipe is placed underneath the holding structure, and preferably above a liner underneath the holding structure. The step of placing at least one pipe underneath the holding structure preferably comprises placing more than one pipe approximately 1-8 feet apart underneath the holding structure, preferably horizontally underneath the holding structure.
In a preferred embodiment of the present invention, the step of disposing at least one sample container within the pipe comprises disposing at least one sample container comprising an absorbent/adsorbent material, and preferably comprises disposing sample containers in series, preferably at intervals, and preferably where the sample containers are detachably connected to each other. Alternatively, the sample container comprises a second pipe slidable in the perforated pipe. Preferably, the sample container comprises a location delineator for identification of placement within the pipe. In a preferred embodiment, the sample container comprises at least one wheel, and alternatively comprises a low-friction bottom surface or a curved bottom surface.
A preferred embodiment of the present invention comprises collecting at least one sample from around the pipe into an absorbent/adsorbent material, preferably bentonite, sand or water. Additionally, collecting at least one sample further comprises collecting in a container comprising a compound indicator, and preferably additionally comprises collecting in a container comprising a reference material.
Alternatively, the invention comprises collecting in a container comprising a reference electrode. Alternatively, the invention comprises collecting the dirt that passes through the perforations.
In a preferred embodiment of the present invention, retrieving the sample cars comprises retrieving with a disposing and retrieving device, preferably retrieving the sample container comprising a loop, a hook, or a magnet on at least one end, and preferably retrieving with cable, string, or cord. The sample container is preferably retrieved with at least one pull connected to at least one retracting activator, preferably a spool, and preferably where each pipe has at least one pull connected to at least one independently-controlled activator. Preferably, the sample containers are retrieved with more than one pull connected to a common spool.
Preferably, the step of analyzing the sample to detect the leaked substance comprises analyzing the absorbent/adsorbent material. Alternatively, the dirt that passes through the perforations is analyzed. Preferably, the step of analyzing the sample comprises analyzing to detect a compound indicator in the substance, and additionally preferably comprises analyzing the sample to detect a reference material in the substance. Preferably, the sample is analyzed to detect the age of the substance. Alternatively, the sample is analyzed to detect the composition of the substance, preferably using an extraction solvent, and more preferably an extraction material. The sample is preferably analyzed to detect the stored material. Additionally, the step of analyzing the sample to detect the leaked substance comprises detecting the source of the substance, preferably whether from a holding structure, a water table, or the environment. Preferably, analyzing the sample detects the volume of the leak.
A primary object of the present invention is to provide an apparatus for detecting leaks under storage tanks or landfills.
Another object of the present invention is to provide an apparatus for localizing the leaks.
A further object of the present invention is to provide an apparatus for leak detection that is easily monitored and allows for assessing the structural integrity.
Yet another object of the present invention is to provide an apparatus for leak detection that is inexpensive to produce.
Still a further object of the present invention is to provide a method of leak detection that is simple and inexpensive.
A primary advantage of the present invention is the ability to localize leaks.
Another advantage of the present invention is the ability to directly sample the leaked substance.
A further advantage of the present invention is the ability to maneuver the sampling cars.
Yet another advantage of the present invention is the prolonged exposure time, thus increasing ability to detect slow or minute leaks.
Still a further advantage of the present invention is the ability to change types of detecting substances.
Other objects, advantages and novel features, and further scope of applicability of the present invention will be set forth in part in the detailed description to follow, taken in conjunction with the accompanying drawings, and in part will become apparent to those skilled in the art upon examination of the following, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.